Table 2 shows that several classes of drugs were associated with the occurrence of incident heart failure. Among the classes with the strongest association were digoxin, antiarrhythmics, vasodilators (mainly nitrates), loop diuretics, and potassium-sparing diuretics. Table 3 presents the results of the Cox regression model analysis with time-dependent variables. Current use of NSAIDs was univariately associated with a 50% increased risk of incident heart failure (RR, 1.5; 95% CI, 1.0-2.3). In patients with a serum creatinine level less than 1.1 mg/dL (100 µmol/L), the univariate RR of the association between NSAIDs and heart failure was 1.4 (95% CI, 0.8-2.4). In patients with a serum creatinine level of 1.1 mg/dL (100 µmol/L) or more, the RR was 2.0 (95% CI, 1.9-5.5). After adjustment for age, sex, hypertension, history of myocardial infarction, atrial fibrillation, renal function at baseline, and concomitant medication, the RR of the association between current NSAID use and the occurrence of incident heart failure declined to 1.1 (95% CI, 0.7-1.7). Among participants who filled at least 1 NSAID prescription, these RRs were univariately 1.4 (95% CI, 0.9-2.1) and, after adjustment, 1.2 (95% CI, 0.8-1.8). In the second analyses in patients who had been followed up since the occurrence of incident heart failure, the crude and adjusted RRs of a relapse of heart failure were 1.4 (95% CI, 0.5-3.8) in both the univariate and the adjusted analyses. As the relapses occurred in those who had had incident heart failure shortly before, baseline hypertension, history of myocardial infarction, a serum creatinine level of 1.1 mg/dL (100 µmol/L) or more, and atrial fibrillation were not associated with a relapse and therefore not adjusted for. Among patients with prevalent heart failure who filled at least 1 NSAID prescription during follow-up, the crude RR of a first relapse of CHF was 3.8 (95% CI, 1.1-12.7). Adjusted for age, sex, and concomitant medication, the RR was 9.9 (95% CI, 1.7-57.0).